There are two versions of this Old Russian name. Obviously it can be
explained only by the influence of Turkic neihgbours of Russian in 10-11 centuries. It disappeared when Russian Orthodox church began to enforce Russian to give their children only Christian names.
1. Rus + Lan = Urys Olany = Russian Child.
Lan (Olan) in Tatar-Mishar dialect means "Child".
2. Arslan=Aryslan>Aruslan>Ruslan. Arslan (Aryslan) means "Lion".
P.S. At the moment the name of Ruslan is widely used by Tatars and other
ethnic minorities of
....and by one Bulgarian:-)